Problems with Running powershell script through PDQ

I'm trying to push out a Desktop link through PDQ.  One line is giving me fits, and I'm not a PS scripting person.

$TargetFile = "$env:SystemRoot\System32\mstsc.exe /v:10.0.1.91"

I've tried it within a ps1 file, as well as scripting directly through PDQ.  There are two issues that keep coming up.

1) the /v always reverts to \v.

2) the colon causes the script to fail.

If I take the colon out of the script, it gets applied, but the link fails.

I've tried various "Fixes" with ` , \ , ' , " and have yet to find the right combination.  Any and all help would be appreciated.

Thanks